1. Field of the Invention
This invention relates to production of vinyl pyrrolidone from 2-pyrrolidone and acetylene in the presence of a strongly basic catalyst, and more particularly, to a method of converting the ethylidene N,N'bis-pyrrolidone by-product of the reaction into 2-pyrrolidone starting material.
2. Description of the Prior Art
Reppe, in U.S. Pat. No. 2,317,804, described a process for preparing vinyl pyrrolidone by reaction of 2-pyrrolidone and acetylene in the presence of potassium hydroxide as a catalyst. The catalyst was prepared separately by reaction of potassium hydroxide with some of the 2-pyrrolidone starting material to produce the potassium salt of 2-pyrrolidone, which then acted as the desired strongly basic catalyst. This catalyst preparation stage then was followed by vinylation of the remainder of the 2-pyrrolidone starting material with acetylene in the presence of the potassium salt of 2-pyrrolidone catalyst.
A by-product of the vinylation reaction, however, has been identified as ethylidene N,N'-bis-pyrrolidinone (EBPY). However, this material was discarded during the process, thus reducing the yield of the desired vinyl pyrrolidone product.
Accordingly, it is the object of this invention to provide a method of converting EBPY into a compound useful in the process of vinylation of 2-pyrrolidone, thus increasing the effective yield of the vinyl pyrrolidone product.